The present invention relates to a wiper device for wiping a vehicle windshield, and more specifically relates to the wiper device having a wiping angle switching function to protect the wiper from snow damage.
Conventional wiper devices have wiping angle switching functions such as that disclosed in Japanese Patent Application No. 60-54655. The wiper device comprises a rotating crank arm, a crank pin fixedly mounted on said crank arm, an eccentric bushing swingably mounted on said crank pin which has a center shaft that is eccentric to the center shaft of the crank pin, a wiper link rod which is mounted so as to be freely swingable relative to the eccentric bushing and actuated reciprocally according to rotation of the crank arm, a wiper blade which swings according to reciprocal actuation of said wiper link rod, and a lever which forms a single unit with the eccentric bushing and is swingable together with said eccentric bushing at the periphery of the crank pin, a slider which is freely slidable in the radial direction of the eccentric bushing when the lever is coupled with said eccentric bushing, said slider being fixedly coupled with said eccentric bushing on the wiper link rod side or crank arm side to change the wiper blade lower reversing position to two stages. The wiper device is installed in a cowl box. An access hole is provided in a fixed position of said cowl box and is covered with a rubber stoper. However, to switch the wiping angle in conventional wiper devices, the user must perform a troublesome series of switching operations such as stop the wiper blade at the upper reversing position, open an engine hood of the car, remove the rubber stopper of the access hole, and switch the fixed position of the sliding member to the wiper link rod's side or the crank arm's side using a screw driver. The switching operations become extremely difficult to perform during snowfall. When the wiper blade housed positon is packed with snow, the wiper blade conflicts with the packed snow before it reaches the lower reversing position, which is a distinct disadvantage from the standpoint of wiper device protection.
U.S. Pat. No. 4,264,997 which is granted in May 5, 1981 discloses a wiper device comprising a rotary output shaft, a wiper shaft connected with a wiping element, a swinging element for converting a rotational movement of the output shaft into a swinging movement of the wiper shaft, the swinging element which includes a crank member rotatably connected to the output shaft, a rocker arm connected with the wiper shaft, a connecting rod turnably connected with the crank member and the rocker arm, and a spring member for permitting swinging of the connecting rod even when the wiper shaft is restricted as a result of snow accumulation in a posterior area of the wiper shaft, for instance.
However, in order to exchange a blade rubber and clean a blade-housed position, the wiper blade must be pulled out from the housed position and be kept maintained in case of applying a structure of the conventional wiper device to a wiper device wherein a wiper blade is fully concealed under an engine hood. Moreover a large current should undersirably flow in a wiper motor so as to swing the connecting rod against the spring member when the wiper shaft is restricted by the snow.